The N-free DARC layer reduces reflectivity at the photoresist interface through optical interference, minimizing CD variation during STI lithography [P1].
The AA N-free DARC Deposition step is inserted in the STI module after the formation of a multilayer hardmask stack consisting of pad nitride, inorganic hardmask, and an amorphous carbon layer, and before subsequent carbon/DARC repetitions and cap oxide deposition to form an optically and etch-balanced…
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